The comprehensive city emission function (CCEF) is developed for a heterogeneous light-emitting or blocking urban environments, embracing any combination of input parameters that characterize linear dimensions in the system (size and distances between buildings or luminaires), properties of light-emitting elements (such as luminous building faÃ§ades and street lighting), ground reflectance and total uplight-fraction, all of these defined for an arbitrarily sized 2D area. The analytical formula obtained is not restricted to a single model class as it can capture any specific light-emission feature for wide range of cities. The CCEF method is numerically fast in contrast to what can be expected of other probabilistic approaches that rely on repeated random sampling. Hence the present solution has great potential in light-pollution modeling and can be included in larger numerical models. Our theoretical findings promise great progress in light-pollution modeling as this is the first time an analytical solution to city emission function (CEF) has been developed that depends on statistical mean size and height of city buildings, inter-building separation, prevailing heights of light fixtures, lighting density, and other factors such as e.g. luminaire light output and light distribution, including the amount of uplight, and representative city size. The model is validated for sensitivity and specificity pertinent to combinations of input parameters in order to test its behavior under various conditions, including those that can occur in complex urban environments. It is demonstrated that the solution model succeeds in reproducing a light emission peak at some elevated zenith angles and is consistent with reduced rather than enhanced emission in directions nearly parallel to the ground.

This paper investigates the illuminance needed to detect trip hazards for pedestrians walking after dark. In previous work, it was assumed that the critical obstacle height is 25&#8201;mm: further review of accident data and foot clearance data suggests instead that 10&#8201;mm is the critical height. Eye tracking records suggest a tendency for obstacles to be detected approximately 3.4&#8201;m ahead. Interpretation of obstacle detection data suggests horizontal photopic illuminances of up to 0.9&#8201;lux are required for peripheral detection of a 10&#8201;mm obstacle 3.4&#8201;m ahead, according to the scotopic/photopic ratio of the lighting and the age of the observer.

1.Light pollution has been increasing around the globe and threatens to disturb natural rhythms of wildlife species. Artificial light impacts the behaviour of insectivorous bats in numerous ways, including foraging behaviour, which may in turn lead to altered prey selection.

2.In a manipulative field experiment, we collected faecal samples from six species of insectivorous bats in naturally dark and artificially lit conditions, and identified prey items using molecular methods to investigate effects of light pollution on prey selection.

3.Proportional differences of identified prey were not consistent and appeared to be species specific. Red bats, little brown bats, and gray bats exhibited expected increases in moths at lit sites. Beetle-specialist big brown bats had a sizeable increase in beetle consumption around lights, while tri-colored bats and evening bats showed little change in moth consumption between experimental conditions. Dietary overlap was high between experimental conditions within each species, and dietary breadth only changed significantly between experimental conditions in one species, the little brown bat.

4.Policy implications. Our results, building on others, demonstrate that bat-insect interactions may be more nuanced than the common assertion that moth consumption increases around lights. They highlight the need for a greater mechanistic understanding of bat-light interactions to predict which species will be most affected by light pollution. Given differences in bat and insect communities, we advocate biologists, land stewards, and civil planners work collaboratively to determine lighting solutions that minimize changes in foraging behaviour of species in the local bat community. Such efforts may allow stakeholders to more effectively craft management strategies to minimize unnatural shifts in prey selection caused by artificial lights.

Bright nocturnal light has been known to suppress melatonin secretion. However, bright light exposure during daytime might reduce light-induced melatonin suppression (LIMS) at night. This study aims to evaluate the effect of high correlated color temperature LED light during daytime on LIMS. Male participants were exposed to different light conditions for 3 h in the morning (09:00â??12:00). The light conditions were dim light (<10 lx), 125 lx high correlated color temperature (CCT) LED light, and 250 lx high CCT LED light. The subjects were then exposed to bright light (white light, 300 lx) for 1.5 h at night (01:00â??02:30). Saliva samples were taken before (01:00) and after (02:30) exposure for evaluation of melatonin secretion. There were no significant differences in melatonin secretion before and after night-time light exposure on the 125 lx and 250 lx morning light conditions. Since these light intensities were almost equal to those in our previous study, the high CCT LED light might be appropriate for certain work places (e.g., hospitals and underground spaces), contributing to the reduction of our health risk and also saving energy.

The lighting of the Church of the Three Kings in Logatec, Slovenia was replaced in 2014. The power of the installation was reduced 96% from 1.6 kW to 58 W, and spill light from the site was effectively eliminated. As a result, the church is no longer visible in nighttime satellite images of the area, indicating a reduction of waste light from the site of at least a factor of 30. This article discusses the concept of sustainability with regards to cultural heritage lighting, within the context of this example.